It may be easier though for game developers to port their games to the aforementioned consoles by porting LÖVE to use Nintendo's SDK, but they will have to do it on their own and won't be able to share that development publicly (much less as open source)

Depends on what you mean by share, I'd guess. You could always publicly say, "I have a port, if you've signed the nintendo NDA you can email me for the code". So it'd be like open source but only within the secret club.

this is exactly how it works.

Oh good, I was under the impression that even this was forbidden by the NDA.

Just out of pure curiosity, does the Nintendo Switch non-disclosure agreement allow for developers to communicate and share with other developers that have also signed the NDA? If so, is there a way to check and verify that someone else has signed the NDA? If so, is it possible for LOVE developers to host a "hidden" or "secluded" section of the website dedicated to people putting their LOVE games on the Nintendo Switch?

"While there is no special code needed for Nintendo Switch support (100% of the platform code is in SDL and BRUTE, two separate projects), all consulting and documentation is private, per NDA requirements."

I'm not currently in a position where I could personally provide that type of service (both because I don't have access to a Switch at home to port love to, and because my full-time day job is a similar line of work), but that doesn't mean someone else wouldn't be able to do it.